The Accept request HTTP header advertises which content types, expressed as MIME types, the client is able to understand. Using content negotiation, the server then selects one of the proposals, uses it and informs the client of its choice with the Content-Type response header. Browsers set adequate values for this header depending on the context where the request is done: when fetching a CSS stylesheet a different value is set for the request than when fetching an image, video or a script.

Header type Request header
Forbidden header name no
CORS-safelisted request header yes, with the additional restriction that values can't contain a CORS-unsafe request header byte: 0x00-0x1F (except 0x09 (HT)), "():<>[email protected][\]{}, and 0x7F (DEL).


Accept: <MIME_type>/<MIME_subtype>
Accept: <MIME_type>/*
Accept: */*

// Multiple types, weighted with the quality value syntax:
Accept: text/html, application/xhtml+xml, application/xml;q=0.9, image/webp, */*;q=0.8


A single, precise MIME type, like text/html.
A MIME type, but without any subtype. image/* will match image/png, image/svg, image/gif and any other image types.
Any MIME type
;q= (q-factor weighting)
Any value used is placed in an order of preference expressed using relative quality value called the weight.


Accept: text/html

Accept: image/*

// General default
Accept: */*

// Default for navigation requests
Accept: text/html, application/xhtml+xml, application/xml;q=0.9, */*;q=0.8


Specification Title
RFC 7231, section 5.3.2: Accept Hypertext Transfer Protocol (HTTP/1.1): Semantics and Context

Browser compatibilityUpdate compatibility data on GitHub

Chrome Edge Firefox Internet Explorer Opera Safari
Accept Yes 12 Yes
In Firefox 66, the default Accept header value changed to */*.
Yes Yes Yes
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
Accept Yes Yes Yes
In Firefox 66, the default Accept header value changed to */*.
Yes Yes Yes

See also

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